“Twice-cooked HDR” – Dealing with extreme contrast

I am sure you know what “twice cooked pork” is (if not – here it is). Basically, the pork is cooked once (boiled), then diced and cooked again (fried in the Wok). If you approach “cooking” the HDR image in the same way as cooking a dish, then it is only logical to try to cook different “ingredients” in different pots and then mix, slice and dice them just before serving the final dish to the table. At least, that’s what I attempted to do with the following image.

Final “twice cooked” HDR

The above image is the interior of the Memorial Church in Stanford, CA. Beside being quite interesting from the architectural point of view, it is also quite challenging to photograph because of the skylight in the cupola. On a sunny day (which is the most typical day in Stanford), the difference between the brightest part (skylight) and the darkest area (deep in the naves) can easily reach about 6 stops, which is not only outside of the physical capability of a single frame capture but also exceed the “plus/minus two stops” bracketing range of my Canon. So… to deal with the situation, I had to “cook” my image twice. Here’s how.

Gathering the ingredients

First, I took 6 frames with 1 EV step (as shown below). This particular location allows tripods (which is rather uncommon but since they do allow it, there was no reason not to take advantage of it).

Why six? Because it allows me to pull much more details in the shadows while keeping the noise in check. Also, the final image is not as “contrasty” as it would have been otherwise. Just for fun, I processed two HDRs using the same parameters – one with all six frames and the other one with only three (the brightest, the darkest and the “normal” one). The difference is fairly obvious:

Cooking the “ingredients”

Now that we have the raw frames, let’s take a brief look at them. Almost immediately, we see that the skylight is almost entirely blown out except for the two darkest frames, and the light ones have some considerable halo around the skylight (and the dome in general). It is fairly obvious that we will need two different sets of parameters to deal with the skylight (and the dome) vs. the interior of the church and the naves. So I got into my “digital kitchen” and started cooking. For HDR processing, I almost exclusively use Photomatrix, which gives me quite a bit of control.

First, I wanted to get a good “base” image with details in shadows. I didn’t care much if the skylight didn’t look good, I just wanted to have as much details in the shadows as I could get without getting too much noise and without creating those ugly “HDR-ish” halos. For the curious, on the left you can see my parameter settings in Photomatrix (I use version 4.2.2). As you can see, I went rather conservatively on the Midtones Adjustments and Saturation. This parameter set resulted in the “base” image below. Not too bad overall, I can see quite a bit of details in the shadows; the contrast is quite low but it does not bother me all too much because the overall image is usable and it is much easier to increase contrast than to decrease it. Also, I am thoroughly unimpressed with the look of the dome – much as expected.

Now that we have the base, let’s go back and “cook” another HDR, this time emphasizing the dome and the skylight. I loaded the source frames back into Photomatrix and dialed in the same parameters, then started playing with the sliders, increasing the contrast and decreasing the highlight brightness. After a short while, I had the following image – my second part for the upcoming “dish”:

As you can see, the details in the shadows took considerable turn to the worse but the dome looks much better now!

Well, now that we have the ingredients, let’s mix them and serve the dish! Here we leave Photomatrix and jump into Photoshop.

Merging the HDRs

This part is probably the easiest one: I simply put both HDR’s on separate layers (the “base” one on top) and start masking, slicing and dicing.

I bring the cupola from the “contrasty” second HDR and while at that, adjust the curves on it to give the image more “pop”. Also, I fix the “vignette” on the floor (bottom left and bottom right corners). My Photoshop layer palette looks like the one on the left – basically, I pick up the entire skylight and a bit of the contrast on the pillars from the second “contrasty” image, while the details in the shadows come from the first “soft” one.

Once I’m done mixing, I drop the image back into the Lightroom and add just a touch of “Clarity” adjustment and sharpening and voila! We have our “twice-cooked HDR” ready. Of course, there are still some issues to be fixed – there are some traces of the original halo around the skylight for example, but overall it is not too bad and I’m satisfied with the outcome – the image is quite usable and the problems are rather minor and another half and hour in Photoshop could easily fix all the remaining issues.

So here it is folks – enjoy and never stop experimenting!

Alex Stepanov, Photographer


2 thoughts on ““Twice-cooked HDR” – Dealing with extreme contrast

  1. Since almost all churches and cathedrals do not allow tripod I decided to use “gorilla pod”. Any experience on it? Should I get it?

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